It is well known to provide flotation aids to would-be drowning victims and others stranded in the sea, lake, river or flood waters. Usually such aids are carried to the victim by a lifeguard or other rescue personnel who use the aid to keep the victim calm and as an alternative to the victim clutching the rescuer with possible fatal results to both victim and rescuer. The problem with this usual, personal delivery approach is that important seconds are lost in effecting rescue since the rescuer has to haul the flotation aid device with him to the victim and can do so only at swimming or boat speeds. In the interim the victim may panic and be lost.
Rescue aid devices which can be thrown toward a victim are known but are generally short range. Thus, the conventional life preserver has the advantage of simplicity and reliability but is awkward to place accurately at any significant distance due to its bulk and doughnut configuration. Other devices, less well known, have been described in the patent literature as useful in providing flotation and in some cases as being projectable to a victim, but these devices appear to depend on chemical, electrical, or explosive actuation and will suffer reliability problems if stored for any length of time before use, particularly in marine environments.
In U.S. Pat. No. 3,812,546 to Witte for example, a spherical shell encloses a toroidal tube and a gas bomb for inflating the tube. Upon contact with water, a strap normally blocking release of gas into the tube for inflation, dissolves, and the released gas inflates the tube giving a flotation device. This apparatus while indicated to be an improvement over pellet activated release devices still is likely to suffer reliability difficulties since its effective operation is dependent on a chemical reaction which can vary with water temperature, water salinity, embrittlement of the strap and degradation of the chemical constituents of the strap, all such processes occuring at an unknown rate over time. In U.S. Pat. No. 3,693,202 to Ohtani another ball device is disclosed, this one responsive to sea water contact with a water soluble tablet to permit discharge of gas from a bomb into the toroidal tube to form a life ring. Again, problems of deterioration of the water soluble tablet over storage time, and water temperature differences can greatly affect performance, an unwanted risk in what is a life and death situation.
A mechanical, rather than chemical, operation is to be preferred. In U.S. Pat. No. 3,070,818 to Fairchild a flotation device is described in which release of compressed gas is effected by manual displacement of a plug. The Fairchild device is not a throwable rescue device, but is intended to be worn at all times by a swimmer who suspects there may be difficulties for him in the water. The device in addition to the inherent problem of having to be worn by a potential victim before it can be useful, unlike the throwable chemical devices discussed above, also suffers from a need to be operated by the victim, a not likely circumstance for reliable operation. A similar device having the advantage of mechanical operation and the disadvantage of requiring victim operation is shown in U.S. Pat. No. 2,173,567 to Shafer. The Shafer life saving apparatus is designed to be worn attached with a bathing suit, this was in 1938 when presumably bathing suits could conceal such an appliance, and for operation required the victim to plunge a needle point into a cartridge and release the gas.
A truly long distance life saving cartridge is taught in U.S. Pat. No. 2,496,479 to Kochner et al. There a grenade launcher, which is of course unlikely to be available at most beaches and rivers, is used to fire a "projectile" toward a victim. Percussion resultant from the projectile hitting the water starts a chain reaction among strings and levers and releases compressed gas into a flotation tube. Apart from the impracticality of the launch mode, the critical sequencing of impact, springs and levers makes this a probably unreliable device, unduly costly, and in all events prone to failure through rusting of the components in a marine environment.
In U.S. Pat. No. 3,059,253 to Sager a buoyancy device which generates a lightweight foam in response to water contact is described, enabling a compact rescue aid but requiring a chemical reaction to obtain flotation and thus subject to all the problems of water variation, temperature variation and progressive deterioration in the foam precursors while awaiting use.
An electrically responsive apparatus is disclosed in U.S. Pat. No. 4,094,028 to Fujiyama et al. There gas is generated in situ by electrical decomposition of selected compounds, all triggered by an electrical ignition. While the use of compressed gas cartridges is avoided, far less certain sources of gas are substituted, all at considerable expense and with many chances for operative failure in the complex chain of elecrochemical reactions needed to take place in prescribed sequence.